Linux Fundamentals

3 min read

Command	Description
`man <tool>`	Opens man pages for the specified tool.
`<tool> -h`	Prints the help page of the tool.
`apropos <keyword>`	Searches through man pages’ descriptions for instances of a given keyword.
`cat`	Concatenate and print files.
`whoami`	Displays current username.
`id`	Returns users identity.
`hostname`	Sets or prints the name of the current host system.
`uname`	Prints operating system name.
`pwd`	Returns working directory name.
`ifconfig`	The `ifconfig` utility is used to assign or view an address to a network interface and/or configure network interface parameters.
`ip`	Ip is a utility to show or manipulate routing, network devices, interfaces, and tunnels.
`netstat`	Shows network status.
`ss`	Another utility to investigate sockets.
`ps`	Shows process status.
`who`	Displays who is logged in.
`env`	Prints environment or sets and executes a command.
`lsblk`	Lists block devices.
`lsusb`	Lists USB devices.
`lsof`	Lists opened files.
`lspci`	Lists PCI devices.
`sudo`	Execute command as a different user.
`su`	The `su` utility requests appropriate user credentials via PAM and switches to that user ID (the default user is the superuser). A shell is then executed.
`useradd`	Creates a new user or update default new user information.
`userdel`	Deletes a user account and related files.
`usermod`	Modifies a user account.
`addgroup`	Adds a group to the system.
`delgroup`	Removes a group from the system.
`passwd`	Changes user password.
`dpkg`	Install, remove and configure Debian-based packages.
`apt`	High-level package management command-line utility.
`aptitude`	Alternative to `apt`.
`snap`	Install, remove and configure snap packages.
`gem`	Standard package manager for Ruby.
`pip`	Standard package manager for Python.
`git`	Revision control system command-line utility.
`systemctl`	Command-line based service and systemd control manager.
`ps`	Prints a snapshot of the current processes.
`journalctl`	Query the systemd journal.
`kill`	Sends a signal to a process.
`bg`	Puts a process into background.
`jobs`	Lists all processes that are running in the background.
`fg`	Puts a process into the foreground.
`curl`	Command-line utility to transfer data from or to a server.
`wget`	An alternative to `curl` that downloads files from FTP or HTTP(s) server.
`python3 -m http.server`	Starts a Python3 web server on TCP port 8000.
`ls`	Lists directory contents.
`cd`	Changes the directory.
`clear`	Clears the terminal.
`touch`	Creates an empty file.
`mkdir`	Creates a directory.
`tree`	Lists the contents of a directory recursively.
`mv`	Move or rename files or directories.
`cp`	Copy files or directories.
`nano`	Terminal based text editor.
`which`	Returns the path to a file or link.
`find`	Searches for files in a directory hierarchy.
`updatedb`	Updates the locale database for existing contents on the system.
`locate`	Uses the locale database to find contents on the system.
`more`	Pager that is used to read STDOUT or files.
`less`	An alternative to `more` with more features.
`head`	Prints the first ten lines of STDOUT or a file.
`tail`	Prints the last ten lines of STDOUT or a file.
`sort`	Sorts the contents of STDOUT or a file.
`grep`	Searches for specific results that contain given patterns.
`cut`	Removes sections from each line of files.
`tr`	Replaces certain characters.
`column`	Command-line based utility that formats its input into multiple columns.
`awk`	Pattern scanning and processing language.
`sed`	A stream editor for filtering and transforming text.
`wc`	Prints newline, word, and byte counts for a given input.
`chmod`	Changes permission of a file or directory.
`chown`	Changes the owner and group of a file or directory.